FIGS. 1A, 1B, and 1C represent a traditional incandescent bulb 11, a fluorescent light tube 13 and a compact fluorescent lamp (CFL) 15 respectively. Generally speaking, traditional lamps and lanterns are not capable of changing properties of the light emitted once they are manufactured. In other words, properties of the light emitted from theses devices are fixed as soon as they are manufactured, and users are not able to change the light properties according to their preferences. For instance, the only option for a user to change the light color of a lamp is to buy another bulb with different light color and replace the original one. However, it will cost extra money to purchase more bulbs and need extra space to store spare bulbs.
The limitation of light properties provided by traditional lamps results in that users have to spend money and time in purchasing and changing extra bulbs in order to have multiple choices of light properties. Although some lamps are combined with controllers for providing advanced functions, these controllers are used to control the interval, period or intensity of the light but not the light color. Besides, although some lamps provide several types of light colors for user to choose, the light colors supported are limited. Therefore, users can select only a certain types of light colors provided when the lamp is produced.
Due to the restrictions on the types of light properties provided by traditional lamps, the flexibility of traditional lamps is confined.